1. Field of the Invention
The present invention relates to a semiconductor optical device and a semiconductor assembly.
2. Description of the Related Art
A semiconductor device including a 90-degree optical hybrid is disclosed in S. Farwell et al., “InP Coherent Receiver Chip with High Performance and Manufacturability for CFP2 Modules”, Optical Fiber Communication Conference 2014, USA, OSA Technical Digest, W11.6 (March 2014).
A 90-degree optical hybrid includes a multi-mode interferometer (MMI) having waveguides provided on a semiconductor substrate. The 90-degree optical hybrid is optically coupled to a plurality of photodiodes by a plurality of waveguides. The characteristics of the multi-mode interferometer change depending on slight manufacturing variations. For this reason, in manufacture of the multi-mode interferometer, photolithography conditions, etching conditions, and other various technical items are adjusted. As a result of such adjustment, a 90-degree optical hybrid having desired performance is manufactured.